Rebuilding curve

I am trying to rebuild this two curves as one:

First curve:

Second Curve:

I Thought I could rebuild it as a degree 4 curve. I have 5 control points summing the two curves.
The thing is when I try to draw a curve (following the control points) it does not match with the curve I want.
I used the ExtractPT in order to recreate the two curves as one with degree 4 .

Can anyone please help me ?

Thanks a lot

Join the curves, then Rebuild.


You can not have a single span curve, such as degree 4 with 5 control points, which is straight for part of it’s length and curved for the other part. That’s fundamental limitation of single span NURBS curves. You will need at least two spans.

Thats great information. Where did you learn that. Is there any theory on how to rebuild ? I already watched videos, but they are not that specific.

Thanks so much

I joined the curves. This is how it looks now:

This is the information regarding the joined curve:

I extracted the points and re build it with a curve (degree 6 and 7Cpoints) following the control points of the original.
It is still deviated:


That is also a single span curve. Number of spans = number of control points - degree.

Why do you want a single span curve?

Is it because some folks say only single span curves and surfaces should be used for “Class A” surfaces? If so it is important to understand that the same folks usually use multiple single span curves and surfaces where needed. And a curved segment connected to a straight segment is an example of where multiple single span curves or a single multi-span curves are needed.

I want simple span curves cause I need to export the model to Modo through MOI. I already did the model without taking care the building on the surfaces. It looks crazy when exported to polygons. Now I made a tryout with the rebuilding of surfaces neatly. The model looks super clean in modo now. I am trying to continue that process. Its truth what you say. the problem that I have is that in some parts of my model my rials are discontinuous.

I think that is the reason I can not continue to do the super neat process. You can see in this prntscreen. My rials are coming from a fillet edged cube. The part where the rials touch the corner its when becomes a little bit messy:

As you said this is the best way I could manage it so far. I am not sure what will happen in modo when this gets to polygons. I will have a denser mesh where the ‘patch’ is.